WordNet sense 1 (a narrow pass (especially one between mountains)):

gorge

WordNet sense 2 (place under suspicion or cast doubt upon):

cloud, corrupt, sully, taint

WordNet sense 3 (make dirty or spotty, as by exposure to air; also used metaphorically):

stain, tarnish, maculate

WordNet sense 4 (spot, stain, or pollute):

befoul, foul